User`s guide

Confi
g
urin
g
Model Libraries 4
-43
How PSpice A/D Uses Model
Libraries
PSpice A/D searches libraries for any information it needs to
complete the definition of a part or to run a simulation. If an up-
to-date index does not already exist, PSpice A/D automatically
generates an index file and uses the index to access only the
model definitions relevant to the simulation. This means:
• Memory is not used up with definitions that your design
does not use.
• There is no memory penalty for having large model
libraries.
• Read-in time is kept to a minimum.
Search order
When searching for model definitions, PSpice A/D scans the
model libraries using these criteria:
• local model libraries before global model libraries
• model library sequence as listed in the Library Files list box
in the Analysis and Include Files dialog box
• local directory (where the current schematic resides) first,
then the list of directories specified in the library search path
in the order given (see Changing the Library Search Path
on
page 4-46)
Handlin
g
duplicate model names
If your model libraries contain duplicate model names, PSpice
A/D always uses the first model it finds. This means you might
need to resequence the search order to make sure PSpice A/D
uses the model that you want. See Changing Model Library
Search Order on page 4-45.
Note
Keep in mind that PSpice A/D searches local
libraries before
g
lobal libraries, if the new model
you want to use is local and the duplicate definition
is
g
lobal, you do not need to make any chan
g
es.
When
y
ou use include
files instead
PSpice A/D treats model library and
include files differently as follows:
• For model library files, PSpice A/D
reads in only the definitions it needs
to run the current simulation.
• For include files, PSpice A/D reads
in the file in its entirety.
This means if you confi
g
ure a model
library (.lib extension) as an include file
usin
g
the Add Include or Add Include*
button, PSpice A/D reads in every
model definition contained in that file.
If the model library is lar
g
e, you may
overload the memory capacity of your
system. However, when developin
g
models, you can do the followin
g
:
1
Initially confi
g
ure the model library
as an include file; this avoids
rebuildin
g
the index files every time
the model library chan
g
es.
2
When your models are stable,
reconfi
g
ure the include file
containin
g
the model definitions as a
library file.
To reconfi
g
ure an include file as a
library file:
1
From the Analysis menu, select
Library and Include Files.
2
Select the include file that you want
to chan
g
e.
3
Click Add Library* or Add Library.
4
Click Delete to remove the include
file entry.